1. Field of the Invention
The present invention relates to an apparatus for comminuting materials, the apparatus including a ring of knives that is arranged around a chipping chamber.
2. Description of the Background Art
Chipping devices of this class are known, for example, as knife ring chippers with an interior striker wheel system, whereby chips are comminuted into fine shavings, which serve as a base material for the production of particle boards. In addition, there are timber chippers, whereby the stationary material is turned into large-size chips by a rotating and transversely-operating knife ring, the chips being further used for manufacturing OSB (Oriented Strand Board) products.
In such devices, the actual comminuting is done by slicing knives that are assembled, together with a knife retaining plate, outside of the chipping apparatus and within a template to form a knife package. The knife packages are held by knife carriers, which are arranged in a circular shape between two carrier rings around an axis of rotation, thus forming a ring of knives. To make it easier to attain the required blade projection, the knife carrier has a stop surface as a reference surface that extends along the entire length of the knife carrier, the reference surface interacting with a oppositely located blade located of the pre-adjusted knife package. This stop surface, which also serves as a reference surface, is also the zero position for the knife packages because from it the control value for the position of the blade of the slicing knife is taken. The main rule for the installation of knife packages is that all blades of the slicing knives travel in the same cutting circle.
However, as a consequence of tolerances generated during production, the stop surfaces of the knife carriers, and thus the reference surfaces for the blade cutting circle of the slicing knives, are not all positioned on one and the same circumferential line in relation to the axis of the knife ring. This leads to uneven blade projections of the slicing knives and thus, to chips of an inferior quality.
For this reason, it is already known from DE 26 28 764 to adjust the reference surface with the aid of an adjustment device to compensate for tolerances generated during production. In DE 26 28 764, the reference surface is formed by an adjustment and set screw, which can be screwed into the knife carrier, or unscrewed therefrom, coplanar to the knife package. The adjustment and set screw thereby serves as a stop for a continuous counter-pressure, and is tightly screwed to the knife package.
A disadvantage of the conventional constructions is that a maximal usable width of the slicing knife is fixed by the distance between the blade of a slicing knife and the reference surface, to which the slicing knife abuts with its rearward longitudinal edge. In view of longer operating times of the wear-prone slicing knives, the use of the widest possible slicing knives would be desirable.